Diagnostics

Every problem the compiler finds is reported as a diagnostic: a severity, a stable code, a message, and the line and column it came from. This page is the catalogue of those codes.

A message is written for a person and gets reworded whenever a clearer wording is found. A code never changes. So a code is what you match on, suppress on, and group by - anything reading the message text breaks the next time the message is improved.

Reading a diagnostic

The CLI prints a diagnostic in the format editors and build servers already parse - the file, the position, the severity, the code, and the message - followed by the offending line and a caret:

nested/broken.play(3,5): error PLAY0028: Unknown slice type 'Wat' - expected StateChange, StateView, Automation or Translate
    3 |     slice Wat DoIt
      |     ^

There are three severities. Error means the document does not compile. Warning means the document compiles but something is very likely wrong - almost always a name nothing declares. Information means something worth knowing that changes nothing.

Why the codes read PLAY

The prefix is PLAY, after the .play documents this compiler reads.

Cratis Arc has its own catalogue, the SP codes, for generating a .play document from C# source. The two run one after the other - Arc generates a document and hands it straight to this compiler to read back - so both sets of diagnostics land in the same build log. A shared prefix would make SP0034 and a compiler code of the same number indistinguishable at a glance and identical to a SP\d{4} filter, which is why the prefixes deliberately have nothing in common. Arc’s codes describe what the generator could not express; the codes here describe what the compiler could not read.

Codes are permanent

A code is an identifier, not a position in a list.

• A number is never reused. When a diagnostic is retired, its number is retired with it and left behind as a gap in the sequence. Handing that number to something else would silently change what an existing suppression means.
• A number is never renumbered. Inserting a code in the middle of the catalogue would change the meaning of every code after it.
• A new code is appended at the end of the sequence whatever it is about, so the number says when a code was added rather than where it belongs. Use this page, not the numbering, to find the codes for an area.
• A code outlives its message. Two constructs hitting the same condition share one code - a property line the parser cannot read reports PLAY0016 whether it sits in a type or in an event.

Reacting to a code

Diagnostic carries the code alongside the severity, the message and the location, so a consumer filters on it directly:

using Cratis.Screenplay;
using Cratis.Screenplay.Diagnostics;

var result = new ScreenplayCompiler().Compile(source);

// A document assembled a piece at a time refers to events the pieces have not introduced yet,
// so that one warning is expected here and everything else is not.
var unexpected = result.Diagnostics
    .Where(diagnostic => diagnostic.Code != DiagnosticCodes.UnknownEvent)
    .ToList();

DiagnosticCodes declares every code in this catalogue as a named constant, so the compiler catches a typo that a string literal would not.

In the editor

The language service behind the VS Code extension and the Monaco editor checks a subset of what the compiler checks, and it reports the compiler’s code for every condition in that subset. So the Unknown type 'Foo' you get as a squiggle and the one the CLI prints are the same PLAY0165, and can be looked up here, filtered on, and matched against a build log:

import { diagnosticCodes, validateLines } from '@cratis/screenplay-language';

const unknownTypes = validateLines(lines).filter((issue) => issue.code === diagnosticCodes.unknownType);

diagnosticCodes names the codes the editor reports, the same way DiagnosticCodes names them for the compiler. A ValidationIssue carries the code as code, and it reaches the editor: a Monaco marker gets it as code, a VS Code diagnostic as Diagnostic.code.

A few editor checks carry no code, deliberately. The capture and projection validators enforce structural rules that no compiler run reports - a capture must include a source block, an append block must include a when clause - and there is no PLAY number for something the compiler never emits. Minting one would make this catalogue describe two different tools, which is the thing the PLAY prefix was chosen to avoid. Those conditions are reported without a code until the compiler checks them too.

The catalogue

The document and its top level

Code	Severity	Reported when
PLAY0001	Error	A line at the top level of a document opens with a word nothing at that level is declared by.
PLAY0002	Error	A domain line is not domain <Qualified.Name>.
PLAY0003	Error	A document declares a domain more than once, and a document has at most one.
PLAY0004	Error	domain is declared after another construct, and it names what the whole document is about.
PLAY0005	Error	An import line is not import <Qualified.Name> [from "<origin>"], or its origin metadata is invalid.
PLAY0006	Warning	A line is indented with tabs, and Screenplay decides nesting from spaces.

Event sources and command streams

Event-source declarations and command stream routes are admitted by ESM v8. Property-path mappings and handler commands remain refused with PLAY0268. Binding reports PLAY0273 for generated mappings, stored-name collisions (including pin-versus-name), the reserved stored source name Default, the reserved stored stream name All (including id "All"), or a routed fixture whose source identifier type cannot be resolved. Reserved-name checks are binding-only; authoring validation still accepts the declarations. For All, rename the stream without retaining that stored-name pin. A stream reference selects a classification, never the identity destination supplied by for. Handler commands may author routes without declaring their returned events.

Code	Severity	Reported when
PLAY0503	Error	An event source or its source-owned stream has invalid syntax, a repeated directive or physical declaration, an invalid rename pin, or an optional, collection or known composite identifier type. Composite stream-id blocks also refuse fewer than two parts, duplicate names, modifiers, children, empty/repeated headers and mixed scalar/block forms. Duplicate physical sources make their child ownership ambiguous.
PLAY0504	Error	A known source’s stream does not resolve uniquely, or a command route or stream-id mapping is invalid, missing or incompatible, including missing, unknown, duplicated or mismatched-shape composite parts. Scalar literals and composite literal parts refuse empty, non-NFC or ill-formed text and integers outside ±9007199254740991 in Double numeric mode. A command identifier or known production destination type differing from the source’s nominal identifier type is refused, never silently retargeted.
PLAY0505	Error	An exact stream Source.Stream header resolves both to one source-owned stream and to a viable imported value type. Both candidates remain visible; neither is selected automatically.
PLAY0506	Error	A known scalar stream-id or composite part type falls outside text and UUID values and their nominal concepts, plus integer-backed concepts. Bare Int is rejected. Other types need a future portable formatting contract. Unavailable imported shapes remain unresolved.
PLAY0507	Information	A source or stream’s rename-only id pin repeats its current name. New declarations omit the pin.
PLAY0547	Error	A specification routing directive or composite part block is malformed, empty, repeated, conflicting, has invalid children, or leaves effective no stream on a given or when append event. Event examples and redelivery locators may carry no stream.
PLAY0548	Error	A when <Command> occurrence declares stream or no stream; the route belongs to the command declaration.
PLAY0549	Error	A specification stream reference is missing or ambiguous, its key mapping is missing or superfluous, or the scalar stream id or composite part is nonliteral or incompatible, or contains empty, non-NFC or ill-formed text or an integer outside ±9007199254740991 in Double numeric mode. Composite routes require every declared part exactly once and refuse unknown/duplicate names and mismatched scalar/block forms.
PLAY0550	Error	A routed given or when append lacks for, a routed identity is not a compatible concrete literal, or a source without identifier has no unambiguous known producer destination type.
PLAY0551	Error	A then route or destination type contradicts the command under test, which is the event’s only producer in the whole model. Other producers defer the comparison.

Command headers are classified against the complete immutable compilation input, including resolved file imports. @stream Qualified.Type, stream String and modified property forms remain properties; production stream = value and stream String = value remain payload mappings. When neither a source nor a property type resolves, the header keeps its legacy property interpretation and unknown-type evidence, including deeper legacy command members. A misspelled source name cannot be distinguished from an unresolved qualified property by spelling alone. Stream-id children do not override this rule. Candidate discovery uses the same inline-language registry as the committed parse; registered code payloads cannot declare sources or property types.

Syntax JSON retains every ambiguous or duplicate header in CommandSyntax.streamCandidates, including its property interpretation when ambiguous. stream holds at most one unambiguous route. Deeper legacy properties remain command members, without duplicating the candidate property. Such invalid drafts cannot be printed or expanded into .play files: export throws InvalidSyntaxJson rather than selecting an interpretation or dropping a header. Retain syntax JSON until you repair the draft. Use @stream for an intended qualified property, or remove the competing type interpretation for an intended route; remove duplicate route headers before export.

Concepts

Code	Severity	Reported when
PLAY0007	Error	A concept line is not concept <Name> : <Type>.
PLAY0008	Error	A concept is declared over a primitive the language does not have.
PLAY0009	Error	A value of an enumeration concept is not an identifier.
PLAY0010	Error	A line in a concept body opens with a word a concept declares nothing by.
PLAY0011	Warning	A value of an enumeration is called validate, which the concept body reads as an empty validate block.
PLAY0012	Error	A concept gives a reason, scope or personal-data qualifier for a marker it does not carry.
PLAY0013	Error	A concept gives the reason for one attribute more than once.
PLAY0515	Error	A concept marked pii or secret is used as a command identifier, an explicit for destination, an event source identifier, a scalar stream id type, a composite stream id part type, or a command route mapping source (including nested property paths). The message names the attribute and position, never a value. A mapping using the same protected concept already reported at its resolved stream-id declaration is not reported again; a different protected source concept is still reported. Specification route literals rely on their declaration’s check. Use a surrogate Uuid identifier and keep personal data or operational secrets as properties. Reaction destinations also check values typed directly in the trigger clause, even for an undeclared or registered trigger. When a reaction source names both an event and a declared trigger, a protected destination in the resolved event shape or the trigger clause is rejected.
PLAY0653	Warning	A concept header repeats a compliance marker, including pii personal. Both compilers keep the first marker for each wire identity and attach body settings to it; canonical printing writes one marker. The concept-line repair removes later tokens with PreserveTrivia.
PLAY0565	Information	Legacy @pii, sensitive or @sensitive spelling. Use bare pii/secret; per-line and document repairs preserve notes and trivia.
PLAY0566	Error	Unknown concept compliance marker; expected pii, personal or secret.
PLAY0567	Error	Scope belongs to secret and must be subject, namespace or global.
PLAY0568	Error	A concept declares secret scope more than once.
PLAY0569	Warning	Explicit secret scope on pii secret is ignored because only Chronicle [PII] renders.
PLAY0570	Error	Invalid personal-data qualifier or unknown Art. 9(1) category.
PLAY0571	Error	A concept declares more than one pii special category.
PLAY0590	Error	An event marks more than one data-subject property; each extra mark names the first. Choose one; no automatic repair is safe.
PLAY0591	Error	A subject must be a required scalar String, Uuid or their concepts, or an Int-backed concept. Optional values, collections, composites, bare Int, enums, Decimal, Bool, Date and DateTime are refused.
PLAY0592	Error	A subject concept is pii or secret; EventContext.Subject is plaintext. Use a surrogate identity.
PLAY0593	Error	The subject modifier belongs only to event properties, not commands, types, operation inputs, trigger or reaction data or response fields (decision 0008).
PLAY0594	Error	Read model subjects are not yet supported; #559 covers the mark and Chronicle’s reserved _subject, __subject and __subjects names.
PLAY0595	Error	Subject is duplicated or out of modifier order. Write each modifier once: Type optional generated identifier subject.

Processing purposes

Code	Severity	Reported when
PLAY0596	Error	Invalid purpose declaration, reference or field syntax.
PLAY0597	Error	Unknown basis, condition or erasure-exception value.
PLAY0598	Error	A purpose repeats a singleton field.
PLAY0599	Error	A purpose name is declared more than once.
PLAY0600	Warning	A purpose reference does not resolve.
PLAY0601	Warning	Interest is declared without basis legitimateInterests, or that basis has no nonblank interest statement.
PLAY0602	Warning	Opt-in purposes check: a slice carries pii without a declared purpose in scope.
PLAY0603	Warning	Opt-in purposes check: special-category data lacks a purpose’s condition.
PLAY0604	Warning	Opt-in purposes check: criminal data lacks a purpose’s authorization.
PLAY0605	Warning	Opt-in purposes check: a purpose has no basis.
PLAY0606	Warning	Opt-in purposes check: a purpose is never referenced.

These are structural findings, not legal verdicts. See Processing purposes.

Types

Code	Severity	Reported when
PLAY0014	Error	A type line is not type <Name>.
PLAY0015	Error	A type declares no properties, and a type is the properties it holds.
PLAY0016	Error	A property line is not <name> <Type>.
PLAY0017	Error	A property outside a command is marked as the identifier, which only a command property can be.

Events

Code	Severity	Reported when
PLAY0018	Error	An event line is not [public] event <Name> [generation <N>] [from "<origin>"], or its visibility/origin metadata is invalid.
PLAY0019	Error	A property of an event is marked as the identifier, and an event never carries its event source id.
PLAY0020	Warning	A property called tag is read by the event body as a static tag rather than as a property.
PLAY0446	Error	An event generation is zero, exceeds the 32-bit generation range, or uses Chronicle’s reserved unspecified value (4294967295).
PLAY0447	Error	The same event in one slice declares a generation twice; two unmarked declarations are both generation 1 and therefore duplicate.
PLAY0448	Error	An event in one slice omits a generation between 1 and its latest generation.

Modules, features, slices and layouts

Code	Severity	Reported when
PLAY0021	Error	A module line is not module <Name>.
PLAY0022	Error	A line in a module body opens with a word a module declares nothing by.
PLAY0023	Error	A feature line is not feature <Name>.
PLAY0024	Error	A line in a feature body opens with a word a feature declares nothing by.
PLAY0025	Error	A slot declared by a layout, screen template or dialog template is not an identifier optionally followed by contributes.
PLAY0026	Error	A line in a layout, screen template or dialog template body opens a block none of them declares anything by.
PLAY0027	Error	A slice line is not slice <Type> <Name>, or direction is malformed, repeated or declared outside Translate. Legacy directionless translations remain accepted.
PLAY0028	Error	A slice is declared with a type the language does not have.
PLAY0029	Warning	A line in a slice body opens with a word a slice declares nothing by.

Personas

Code	Severity	Reported when
PLAY0030	Error	A persona line is not persona <Name>.
PLAY0031	Error	A policy line in a persona body is not policy <Name>.
PLAY0032	Error	A line in a persona body opens with a word a persona declares nothing by.

Commands

Code	Severity	Reported when
PLAY0033	Error	A command line is not command <Name>.
PLAY0034	Error	A line in a command body opens with a word a command declares nothing by.
PLAY0035	Error	A command declares both produces and handler, which say the same thing two ways.
PLAY0036	Error	A command marks more than one property as its identifier.
PLAY0037	Error	A concurrency line carries anything beyond the keyword.
PLAY0038	Error	A command declares more than one concurrency block, and a command has at most one.
PLAY0039	Error	A line in a concurrency block names a dimension the block does not have.
PLAY0040	Error	A dimension of a concurrency block is not written the way that dimension is written.
PLAY0041	Error	A concurrency block states one dimension more than once.
PLAY0042	Error	A produces line is neither produces <EventType> nor produces when <condition>.
PLAY0043	Error	A produces when condition is followed by no event to produce.
PLAY0044	Error	A mapping line is not <property> = <source>.
PLAY0045	Error	A handler names neither a file, an inline code block nor an explicit implementation wrapper.
PLAY0046	Error	A line in a handler body opens with a word a handler declares nothing by.

Queries

Code	Severity	Reported when
PLAY0047	Error	A query line is not query <Name> => [observable] <ReadModel>.
PLAY0048	Error	A line in a query body opens with a word a query declares nothing by.
PLAY0049	Error	A by or filter parameter is not <keyword> <name> <Type> [from <source>].
PLAY0050	Error	A performer line carries anything beyond the keyword.
PLAY0051	Error	A query declares more than one performer, and a query has at most one.
PLAY0052	Error	A performer names neither a file nor an inline code block.
PLAY0053	Error	A line in a performer body opens with a word a performer declares nothing by.

Projections

Code	Severity	Reported when
PLAY0054	Error	A projection document holds a top level line that does not open a projection.
PLAY0055	Error	A projection document declares no projection at all.
PLAY0056	Error	A projection line is not projection <Name> [=> <ReadModel>].
PLAY0057	Error	A projection declares no directives, so it builds nothing.
PLAY0058	Error	A line in a projection body opens with a word a projection declares nothing by.
PLAY0059	Error	A projection declares more than one key.
PLAY0060	Error	A from block declares more than one key.
PLAY0061	Error	A from line names no event to read from.
PLAY0062	Error	An event reference is not a name the language can read as one.
PLAY0063	Error	A join line is not join <property> on <key>.
PLAY0064	Error	A join block holds a line that is not with <EventType>.
PLAY0065	Error	A children line is not children <collection> identified by <key>.
PLAY0066	Error	A nested line is not nested <property>.
PLAY0067	Error	A nested block reads from no event, so nothing ever fills it.
PLAY0068	Error	A remove line is neither remove with <EventType> nor remove via join on <EventType>.
PLAY0069	Error	A remove block holds a line other than parent.
PLAY0070	Error	A clear line is not clear with <EventType>.
PLAY0071	Error	clear with is written where there is nothing to clear.
PLAY0072	Error	A part of a composite key is not <property> = <expression>.
PLAY0073	Error	A composite key part is a template expression, which a key cannot be.
PLAY0074	Error	A composite key declares no parts.
PLAY0075	Error	A mapping line in a projection is not one the language can read.
PLAY0452	Warning	More than one automap or no automap appears in the same projection scope. The last setting wins; printing preserves the authored settings and their individual comments.
PLAY0514	Warning	A projection mapping, children, or nested target is absent from the declared read-model or element shape. Unknown or imported shapes are not guessed.

Captures

Code	Severity	Reported when
PLAY0076	Error	A capture document holds a top level line that does not open a capture.
PLAY0077	Error	A capture document declares no capture at all.
PLAY0078	Error	A capture line is not capture <Name>.
PLAY0079	Error	A line in a capture body opens with a word a capture declares nothing by.
PLAY0080	Error	A map entry is not <property> = <source> [translate].
PLAY0081	Error	A translation is not "<source>" => <target>.
PLAY0082	Error	A split line is not split <property> by "<separator>".
PLAY0083	Error	A target of a split is not a property path.
PLAY0084	Error	An append line is not append <EventType>.
PLAY0085	Error	A line in an append body opens with a word an append declares nothing by.
PLAY0086	Error	A when line names no trigger.
PLAY0087	Error	A when clause is not one of the shapes a trigger is written in.
PLAY0088	Error	A value transition is not when <Path> from <value> to <value>.
PLAY0089	Error	A when clause combines properties with both and and or.
PLAY0090	Error	A when combinator is followed by no property.
PLAY0091	Error	A line in a children or nested block is neither map nor append.

Specifications

Code	Severity	Reported when
PLAY0092	Error	A specification document holds a top level line that opens neither a specification nor an example.
PLAY0093	Error	A specification document declares no specification at all.
PLAY0094	Error	A specification line is not specification <Name>.
PLAY0095	Error	A line in a specification body opens with a word a specification declares nothing by.
PLAY0096	Error	A when line is not when <CommandType>.
PLAY0097	Error	A specification issues more than one command, and a specification is one example.
PLAY0098	Error	A then error line is neither then error nor then error "<reason>".
PLAY0099	Error	A given readmodel or then readmodel line does not name a read model type.
PLAY0100	Error	A given or then line does not name an event type.
PLAY0101	Error	A value a specification step states is not <property> = <value>.
PLAY0453	Error	A then no readmodel line lacks a view or key, uses exactly, or has child mappings.
PLAY0518	Error	An example declaration is not example <Name> : <EventOrCommandOrReadModel>.
PLAY0519	Error	A fixture assigns the same property more than once, including across a step’s inline assignment and indented body. Assign it once; overriding a value from an example is a separate operation.
PLAY0520	Error	An example’s type or reference is unknown, ambiguous, or not an event, command, or read model. Qualify the declaration; example inheritance is not supported.
PLAY0521	Error	An example name collides with a type name or repeats in the same scope. Choose a distinct example name.
PLAY0522	Error	A step references an example of another kind. Use the corrected step spelling suggested by the diagnostic.
PLAY0523	Error	An example supplies an undeclared current-generation property, an invalid generated fixture, or for on a read model. Use only the current type’s allowed fixture lines.
PLAY0524	Error	Binding an exact-shape specification step found a missing required property after expansion. The diagnostic names the step, property, and example when used. Supply the property in the example or step; no defaults are assumed.
PLAY0525	Error	Semantic admission found a stated example value incompatible with its type, or for without one unambiguous required scalar destination type. Fix the value or its destination contract, even if the example is unused or that value is overridden. Partial top-level examples remain allowed. Ordinary fixture diagnostics also apply to null, nonconcrete, structured and generated values.
PLAY0526	Error	A command or read-model example states a route. Only event examples carry routes; a command’s route comes from its declaration, and read models have none. Top-level streamId = value is payload, not route metadata.

Screens

Code	Severity	Reported when
PLAY0102	Error	A screen line is not screen <Name>.
PLAY0103	Error	A line in a screen body opens with a word a screen declares nothing by.
PLAY0104	Error	A data line is not data <ReadModel> via query <Query> [by <param>].
PLAY0105	Error	An action line is not action <Command>.
PLAY0106	Error	A line in an action body is neither label nor navigate to.
PLAY0107	Error	A navigation is not navigate to <Screen> [by <param>].
PLAY0108	Error	A line under a screen layout does not name a slot.
PLAY0109	Error	A title line is not title "<text>".
PLAY0110	Error	A line in a table body is neither column nor on row-click navigate to.
PLAY0111	Error	A line in a summary body is not field <property> label "<text>".

Policies and authorization

Code	Severity	Reported when
PLAY0112	Error	A policy line is not policy <Name>.
PLAY0113	Error	A line in a policy body is neither require nor an inline code block.
PLAY0114	Error	A policy states nothing it requires of the caller.
PLAY0115	Error	A policy condition holds a token the language has no reading for.
PLAY0116	Error	A policy requirement states no condition.
PLAY0117	Error	A group opened in a policy condition is never closed.
PLAY0118	Error	A role requirement names no role.
PLAY0119	Error	A claim requirement names no claim.
PLAY0120	Error	A claim requirement does not say what the claim is matched against.
PLAY0121	Error	A claim match states nothing to match the claim to.
PLAY0122	Error	An authorize clause names no policy.
PLAY0123	Error	A policy is referred to by something that is not a policy name.
PLAY0440	Error	A policy combines require with an inline code block or a file implementation. Choose one form.
PLAY0441	Error	A policy has more than one require line; combine the conditions with and/or in one require.

Authentication

Code	Severity	Reported when
PLAY0124	Error	An authentication line carries anything beyond the keyword.
PLAY0125	Error	A document declares more than one authentication block, and a document has at most one.
PLAY0126	Error	A provider line is not provider <Name>.
PLAY0127	Error	A setting of a provider is not <name> <value>.

Event seeding

Code	Severity	Reported when
PLAY0128	Error	A seed line carries anything beyond the keyword.
PLAY0129	Error	A seed group is not for "<event source id>".
PLAY0130	Error	A line in a seed group does not name an event type.
PLAY0131	Error	A value a seeded event carries is not <property> = <value>.

Constraints

Code	Severity	Reported when
PLAY0132	Error	A constraint line is not constraint <Name>.
PLAY0133	Error	A constraint states nothing it holds the application to.
PLAY0134	Error	A line in a constraint body is not one the language can read.
PLAY0135	Error	A constraint mixes unique event and unique property rules, combines a file rule with another rule, repeats a singular option, or repeats a target, release, or property. An event cannot both claim and release the same constraint. Several distinct unique rules of the same kind are allowed.

Reactions

Code	Severity	Reported when
PLAY0136	Error	A reaction line is not reaction <Name>.
PLAY0137	Error	A line in a reaction body is not a trigger the language reads.
PLAY0138	Error	A reaction states no trigger, so nothing ever sets it off.
PLAY0139	Error	A line in a reaction trigger body opens with a word a trigger declares nothing by.

Validation rules

Code	Severity	Reported when
PLAY0140	Error	A validate line is neither validate nor the deprecated validate csharp form.
PLAY0141	Error	A validation rule is not one the language can read.
PLAY0142	Error	A validation rule names a rule the language does not have.
PLAY0143	Error	A rule line does not name the rule with an identifier.
PLAY0144	Error	A named rule names neither a file nor an inline code block.

Descriptions and tags

Code	Severity	Reported when
PLAY0145	Error	A description line is not description "<text>".
PLAY0146	Error	A fenced description holds no text.
PLAY0147	Error	Something is described more than once, and a description is given once.
PLAY0148	Error	A tag line carries no value.
PLAY0149	Error	A tag value is neither an identifier, a string literal nor a context expression.

Expressions

Code	Severity	Reported when
PLAY0150	Error	A literal expression carries no value.
PLAY0151	Error	A $causedBy expression names a property the cause does not carry. The short form admits what the event context catalog lists below causedBy: subject, name, userName and onBehalfOf, which is itself an identity with the same members.
PLAY0152	Error	An expression is not one the language can read.
PLAY0153	Warning	A $context path opens with a root the context does not have.
PLAY0154	Warning	A $context.causedBy path names a property the cause does not carry.
PLAY0155	Warning	A $identity or $context.identity path names a property the caller identity does not carry.
PLAY0156	Error	A template expression is never closed.
PLAY0157	Error	An interpolation inside a template expression is never closed.

Conditions

Code	Severity	Reported when
PLAY0158	Error	A condition holds a token the language has no reading for.
PLAY0159	Error	A condition is expected and nothing is written.
PLAY0160	Error	A group opened in a condition is never closed.
PLAY0161	Error	A comparison states what is compared and not how.
PLAY0162	Error	A comparison states nothing to compare against.

Inline code

Code	Severity	Reported when
PLAY0163	Error	A construct opening an inline code block is followed by no fence.
PLAY0164	Error	An inline code block is never closed.

Names the document does not resolve

Code	Severity	Reported when
PLAY0165	Warning	A property names a type nothing in the document or its imports declares.
PLAY0166	Warning	An event is referred to that nothing in the document or its imports declares, including projection remove with, remove via join on, and capture append.
PLAY0167	Warning or error	A policy is referred to that nothing in the document declares. A persona’s unknown policy is an error during compilation, Safe authoring, and executable binding. Draft authoring retains it as a warning with explicit unresolved-reference debt; other unresolved policy references are warnings.
PLAY0168	Error	A concept and a type, or two of either, are declared under one name; also reused when an inline event repeats a typed payload property name.
PLAY0169	Error	An authentication block declares two providers under one name.
PLAY0170	Error	A seed block seeds nothing.
PLAY0171	Error	A concurrency block narrows nothing.

A folder compiled as one application

Code	Severity	Reported when
PLAY0172	Error	Two files of a folder each declare something the application has at most one of.
PLAY0173	Error	Two files of a folder declare the same name.
PLAY0174	Warning	Two files of a folder describe the same thing differently, and the first description is kept.

What a command or reaction trigger reads to decide

Code	Severity	Reported when
PLAY0175	Error	A reads line is not reads <ReadModel> [as <alias>] [by <value>] (or the header of a child by mapping block), or uses as, by, or reads as an alias. Under a reaction trigger, a bare reads line suggests @reads for a value named reads.
PLAY0177	Warning	A command or reaction trigger reads a read model no projection in the document produces.
PLAY0178	Warning	The by of a command’s reads declaration does not name a property of the command.
PLAY0442	Warning	A reaction trigger reads by a value it does not take.
PLAY0443	Error	A clock trigger reads by a value, but clock triggers take no values.
PLAY0444	Warning	A reaction trigger reads a primitive type name as a view; use @reads <PrimitiveType> if reads is a trigger value.
PLAY0451	Error	A reads line in a command or reaction trigger has children other than one by block, or combines that block with a single by value. Invalid children are skipped, not parsed as owner values or properties.

Rules about the whole artifact

Code	Severity	Reported when
PLAY0179	Error	A require rule carries no condition.
PLAY0180	Error	The body of a require rule holds something other than its message.
PLAY0181	Warning	A require operand is qualified by something the command does not read.
PLAY0182	Warning	A require operand names neither a property of the artifact nor state it reads.

Authentication provider configuration

Code	Severity	Reported when
PLAY0183	Error	An authentication provider carries a configuration body, which belongs where the application runs.

Authorize

Code	Severity	Reported when
PLAY0184	Error	Tokens are left over after the requirement of an authorize.
PLAY0185	Error	A parenthesised group in an authorize is never closed.

Read models and reducers

Code	Severity	Reported when
PLAY0186	Error	A readmodel line is not readmodel <Name>.
PLAY0187	Error	A reducer line is not reducer <Name> => <ReadModel>.
PLAY0188	Error	A line in a reducer body is not an on <EventType> rule.
PLAY0189	Error	A reducer declares no rule, so nothing it observes is stated.
PLAY0190	Error	The body of a reducer rule holds something other than a description, a file or inline code.
PLAY0191	Error	More than one projection or reducer builds the same read model.
PLAY0192	Error	A document declares the same read model more than once.
PLAY0398	Error	A reducer has some on rules with transition bodies and others without them. Give every rule an inline or file body.
PLAY0399	Error	A reducer observes the same resolved event in more than one on rule.

Where a produced event lands, and what a reaction sets off

Code	Severity	Reported when
PLAY0193	Error	A produces declares more than one for, and an event is appended to one event source.
PLAY0194	Error	An invokes line is not invokes <Command>.
PLAY0195	Warning	A reactor invokes a command the document does not declare.

What a screen binds to

Code	Severity	Reported when
PLAY0196	Warning	A screen binds data to a query nothing in scope declares.
PLAY0197	Warning	A screen navigates to a screen nothing in scope declares.
PLAY0198	Warning	A bare name matches more than one declaration at the same depth, or a qualified name matches more than one trailing container path, so which one it means is undecided. See declared dependency targets.

What a query’s results are narrowed to

Code	Severity	Reported when
PLAY0199	Error	A scoped line is not scoped to <scope>.
PLAY0200	Error	A query declares more than one scope, and results are narrowed one way.

UI profiles

Code	Severity	Reported when
PLAY0201	Error	A ui profile line is not ui profile <Name>.
PLAY0202	Error	Two ui profile blocks in the same document declare the same name.
PLAY0203	Error	A target line under a ui profile is neither target platform ... nor target size ....
PLAY0204	Error	A ui profile declares target platform or target size more than once.
PLAY0205	Error	A line under a packages block is not a valid package name.
PLAY0206	Error	A ui profile’s packages block lists the same package more than once.
PLAY0207	Error	A line in a ui profile body is not target or packages, or packages is declared more than once.

Forms

Code	Severity	Reported when
PLAY0208	Error	A form line is not form <Name> for <Command>.
PLAY0209	Error	Two form blocks in the same document declare the same name.
PLAY0210	Error	A line in a form body is not populate, field or on submit.
PLAY0211	Error	A populate line is neither populate via query ... nor populate from item.
PLAY0212	Error	A form declares populate more than once.
PLAY0213	Error	A field line is not field <property> [from <source>|compose using <Callback>] [label "..."].
PLAY0214	Error	An on submit line is not on submit navigate to <Screen> [by <param>].
PLAY0215	Error	A form declares on submit more than once.
PLAY0216	Warning	A field binds to a property its form’s command does not declare.

Contributions

Code	Severity	Reported when
PLAY0217	Error	A contribute line is not contribute to <ContributionPoint>.
PLAY0218	Error	A line in a contribute to body is not navigate, label or order.
PLAY0219	Error	A contribution declares navigate to more than once.
PLAY0220	Error	A contribution declares label more than once.
PLAY0221	Error	A contribution declares order more than once.
PLAY0222	Error	A contribution’s label line is not label "..." or label $strings.....
PLAY0223	Error	A contribution’s order line is not order <number>.
PLAY0224	Warning	A contribution names a contribution point nothing in scope declares.

Themes

Code	Severity	Reported when
PLAY0225	Error	A theme line is not theme <Name>.
PLAY0226	Error	Two theme blocks in the same document declare the same name.
PLAY0227	Error	A line in a theme body is not compatible with <Package>.
PLAY0228	Error	A theme declares compatibility with the same package more than once.
PLAY0229	Error	A ui profile’s theme line is not theme <Name>.
PLAY0230	Error	A ui profile declares theme more than once.
PLAY0231	Warning	A ui profile selects a theme nothing in the document declares.
PLAY0232	Warning	A ui profile selects a theme not declared compatible with one of the profile’s own packages.

Arrangement

Code	Severity	Reported when
PLAY0233	Error	An arrangement line is not arrangement flow or arrangement freeform.
PLAY0234	Error	A layout, screen template or dialog template declares arrangement more than once.
PLAY0235	Error	A row, column or grid line in an arrangement is malformed.
PLAY0236	Error	A slot leaf within an arrangement tree has malformed sizing attributes.
PLAY0237	Error	A when override line in an arrangement is not a valid width/height size-class condition.
PLAY0238	Error	An arrangement declares more than one when override for the same width/height size-class combination.
PLAY0239	Error	An arrangement block’s body does not match its mode - a flow arrangement declares a variant, or a freeform arrangement declares anything other than one.
PLAY0240	Error	A variant line is not variant width <compact|regular>, height <compact|regular>.
PLAY0241	Error	An arrangement declares more than one variant for the same width/height size-class combination.
PLAY0242	Error	A place line is not place <Slot> hidden or place <Slot> at x,y size w,h.
PLAY0243	Error	A variant places (or hides) the same slot more than once.
PLAY0244	Warning	A freeform arrangement’s variant does not mention (place or hide) a slot another variant of the same arrangement places.

Public event boundaries

These whole-model C# checks run after file assembly and also on programmatic syntax passed to the semantic binder. Public metadata and explicit direction select ESM v9 once these checks pass; a model that fails them never binds. Unknown and ambiguous references retain PLAY0166 and PLAY0198, rather than being guessed private/local. Private origins continue to use the existing invalid event/import declaration diagnostics.

Code	Severity	Reported when
PLAY0607	Error	A command produces a public event. Move publication to an outbound Translate slice.
PLAY0608	Error	A local public event is produced outside an explicitly outbound Translate slice.
PLAY0609	Error	An outbound Translate slice produces zero or multiple distinct local public event types. Repeated productions of the same type count once.
PLAY0610	Error	A foreign public event is consumed outside an explicitly inbound Translate slice.
PLAY0611	Error	An outbound translation consumes a public or foreign event rather than a private local event.
PLAY0612	Error	An inbound translation produces a public or foreign event rather than a private local event.
PLAY0613	Error	A foreign public event is produced locally. Translate it to a private event instead.
PLAY0614	Error	A Translate slice declares or uses public event metadata without explicit direction. Legacy translations without public metadata remain historically inbound. C# and the editors repair it when exactly one direction fits.
PLAY0615	Error	An outbound translation contains an external-data capture instead of consuming private local events.
PLAY0616	Error	An explicitly inbound translation consumes a private or local event instead of a foreign public event.
PLAY0617	Error	An outbound translation produces a private event instead of its one local public event.
PLAY0618	Error	A projection or reducer targets an event (projection X => SomeEvent) outside an explicitly outbound Translate slice.
PLAY0619	Error	A capture reads source events outside an explicitly inbound Translate slice.
PLAY0620	Error	A source events block has no from <Event> line, a line that is not from <Event>, an invalid event name or a repeated event.
PLAY0687	Error	A capture’s source events originate from several event stores; split it into one capture per origin.

The operational edges checked are seed appends, command and reaction productions (including refusal branches), capture appends, projection event sources and joins/removals, reducers and constraints. Projection all includes every declared contract; every only maps the projection’s existing inputs. Specification fixtures are not operational edges. A projection or reducer whose => target resolves to an event (and not to a declared read model) is an event-target projection: its target counts as an output of the slice and its from/on events as inputs, so PLAY0609, PLAY0611, PLAY0613 and PLAY0617 apply to it, and PLAY0618 reports one outside an explicit outbound translation. Each from <Event> under source events counts as an input of the capture, so PLAY0610, PLAY0614 and PLAY0616 apply, and PLAY0619 reports source events outside an explicit inbound translation. Both forms bind and select ESM v9. Existing syntax restrictions remain: qualified reaction triggers do not parse, and qualified event productions still report PLAY0497. Programmatic qualified references are resolved and checked, not treated as private. The TypeScript compiler and both editors report the same codes (see editor diagnostics).

Repairs: only PLAY0614 has one. It declares direction inbound or direction outbound on the slice, and is offered only when exactly one direction is consistent with the slice’s events and constructs (C# propose-repair and read-workspace view repairs over MCP; the TypeScript quick fix in Monaco and VS Code). Every other code in this section has no automatic repair because each one is a contract decision for the author, not a spelling: PLAY0607, PLAY0608, PLAY0613 and PLAY0617 would change which events a slice publishes or produces; PLAY0609, PLAY0611, PLAY0612 and PLAY0616 would change which events a translation consumes or produces, or its direction; PLAY0610, PLAY0615, PLAY0618 and PLAY0619 would move a construct between slices or change its direction; PLAY0620 is malformed source events input with no single intended correction. PLAY0687 requires splitting a capture by origin, with no single intended correction.

Production routes and observer filters

Code	Severity	Reported when
PLAY0663	Error	A reaction or refusal-branch production declares a stream route. Only command event productions can override a route.
PLAY0664	Warning	A production repeats its command’s source, stream and stream-id mappings. The typed workspace repair removes the override.
PLAY0665	Error	An observer filter is malformed, duplicated, has children, names an unresolved or ambiguous source/stream, or a filtered reaction has a non-event trigger.
PLAY0666	Warning	A reaction or reducer filter excludes every statically known producer’s effective route. Handlers and foreign origins are unknown and suppress this C#-only warning.
PLAY0667	Error	Enum members mix explicit numbers with unnumbered members. Number all members or none.
PLAY0668	Error	An enum declares the same number more than once; aliases are not supported.
PLAY0669	Error	An enum member number is outside the int32 range.
PLAY0670	Error	An enum member number is malformed: use decimal digits with an optional minus, no leading zero, fraction, exponent or plus.
PLAY0671	Information	Opt-in completeness hint (enum-pinning or PLAY0671; also included in all) for an unnumbered enum used by an event property. Ordinary compilation does not report it. The numbering refactoring pins each member’s current position; this is not a correctness repair.
PLAY0672	Error	Unknown generation strategy; use the closed strategy set.
PLAY0673	Error	Missing or malformed generation argument or modifier value.
PLAY0674	Error	Generation modifier not allowed for this strategy or primitive.
PLAY0675	Error	Generation modifier repeated; write each at most once.
PLAY0676	Error	Concept declares generation more than once.
PLAY0677	Error	Generation strategy incompatible with the concept primitive.
PLAY0678	Error	Prefix modifier is not printable ASCII or exceeds 32 characters.
PLAY0679	Error	NanoID alphabet must be distinct printable ASCII of size 2..256.
PLAY0680	Error	TypeID prefix is not empty or 1..63 lowercase letters/underscores starting and ending with a letter.
PLAY0681	Error	NanoID size outside 1..256 or bytes count outside 1..512.
PLAY0682	Error	Binding refuses reserved sequence generation until #619.
PLAY0683	Warning	Generated property has fewer than 64 random bits; names the approximate 1% collision draw count. Suppressed when a unique constraint covers its mapped event property.
PLAY0684	Error	Generated identifier has fewer than 64 random bits.
PLAY0685	Error	A returned name is used under the returning command’s on failure. Use it in on success instead; form fields and behavior parameters keep their existing meaning, and an outer successful response remains available.
PLAY0688	Error	A generated concept’s strategy can violate a rule. The diagnostic is on the rule and names the strategy and a quoted witness, regardless of the rule’s severity. Review the strategy-derived matches replacement repair; it also changes validation of input and stored values.
PLAY0689	Warning	Consistency is Unproven for a generated concept rule; names the opaque/outside-fragment/budget/timeout reason. Passing samples are not proof.

Overrides reuse PLAY0504 for route shape, mapping, destination type and duplicate-route errors. Protected sources reuse PLAY0515. Property paths remain refused at binding with PLAY0268 (#574), and generated route inputs with PLAY0273.

Screen composition

These checks run on the assembled model. The source stays in the syntax tree, so an authoring tool can still show and repair it.

Code	Severity	Reported when
PLAY0621	Error	An exposure for <Owner> header or one of its property lines is malformed, or names an unknown collection operation.
PLAY0622	Error	An exposure’s owner is not a layout, screen template or dialog template.
PLAY0623	Error	Re-exposures of one component property form a cycle.
PLAY0624	Error	A reexposes <Owner> names an owner that does not expose the same component property.
PLAY0625	Error	An instance header or one of its set, items, item or item value lines is malformed.
PLAY0626	Error	An instance is not a screen, screen template or dialog template.
PLAY0627	Error	An instance stores a value for a component property no exposure exposes.
PLAY0628	Error	An instance uses set on a collection exposure, or items on a single-value exposure.
PLAY0629	Error	A template’s content <slot> names a slot the template does not declare.
PLAY0630	Error	A navigation’s outlet <name> names an outlet no layout, template or component declares.
PLAY0631	Error	A screen or scoped template assignment uses a template whose scopes exclude that scope.
PLAY0632	Error	A component comes from a package no ui profile declares. Only checked when at least one profile declares packages.
PLAY0654	Error	A navigation contribution’s destination outlet or destination dialog names an outlet or dialog template nothing declares.
PLAY0655	Error	A screen’s contribute to <Point> names a contribution point no layout or template slot declares. Unlike a module or feature contribute to (PLAY0224, a warning), screen contributions belong to the screen-composition checks.
PLAY0656	Error	Template content nests templates in a cycle: a template’s content uses itself, directly or through other templates.

Identity details

Code	Severity	Meaning
PLAY0633	Error	Invalid identity header; write the bare identity keyword.
PLAY0634	Error	More than one identity block in a document. A second file’s block uses the existing folder singular-declaration diagnostic.
PLAY0635	Error	Invalid typed detail line or escape source; each detail has exactly one source.
PLAY0636	Error	Unknown identity source kind; use from claim, from query, inline code or a file.
PLAY0637	Error	Identity detail has neither a declarative source nor an implementation.
PLAY0638	Error	A claim/query detail has a body; refresh and caching belong to the runtime.
PLAY0639	Error	Duplicate identity detail name.
PLAY0640	Error	Detail redeclares id, name, userName, isAuthenticated, roles or claims.
PLAY0641	Error	Identity query source names an unknown or ambiguous query.
PLAY0642	Error	Identity source query is unkeyed or returns a list rather than one result.
PLAY0643	Error	Identity query source omits by <expression>.
PLAY0644	Error	Identity query key reads something other than token built-ins, claims or literals.
PLAY0645	Error	Source query’s authorization depends on additional identity details.
PLAY0646	Error	Query result type or optionality does not match the declared detail type.

Unknown detail types reuse PLAY0165; unknown caller properties reuse PLAY0155. Executable detail reads report PLAY0268, naming the detail and its pending admission (#600). See identity details.

None of these has an automatic repair: each is a composition decision for the author.

Read-model keys

Code	Severity	Reported when
PLAY0660	Error	key is marked outside a top-level read-model property, combined with another modifier, or has an optional or collection type. A part of a multipart key cannot have a composite type.
PLAY0661	Error	A single-instance lookup omits key parts. The message names the missing parts. Command reads have a typed repair when every missing part has one same-named compatible source. Queries and trigger reads are not repaired. Scalar screen, form and navigation lookups cannot supply composite keys.
PLAY0662	Error	A by block has fewer than two distinct parts, names an unknown part, uses the wrong key shape or supplies an incompatible, optional, collection or literal source. A single-instance query must agree with the declared key. No automatic repair is offered.

An explicit single key binds byte-identically to an inferred identifier. Composite keys and by-block queries are authoring-only: binding reports PLAY0268 citing #599.

Triggers

Code	Severity	Reported when
PLAY0245	Error	A trigger line is not trigger <Name>.
PLAY0246	Error	A line in a trigger body is neither a description nor a value the trigger provides.
PLAY0247	Error	The document declares two triggers by the same name, leaving no answer to which one a reaction means.
PLAY0248	Warning	A when line names neither an event nor a trigger the document or the compiler knows.
PLAY0249	Error	An every line is not every <n> <seconds|minutes|hours|days>.
PLAY0250	Error	An at line is not at <HH:mm>, optionally followed by on <Weekday> or on day <n>.
PLAY0251	Warning	A reaction takes a value from an occurrence that the trigger does not provide.
PLAY0252	Error	A reaction states more than one where, and a reaction is narrowed by one condition.
PLAY0253	Error	A reaction declares the same trigger more than once, so the second says nothing the first did not.
PLAY0450	Error	A value line appears under an every or at reaction trigger; clock triggers take no values.

Layouts, screen templates and dialog templates

Code	Severity	Reported when
PLAY0254	Error	A screen template line is not screen template <Name>.
PLAY0255	Error	A dialog template line is not dialog template <Name>.
PLAY0256	Error	A fits slot line is not fits slot <name>.
PLAY0257	Error	A screen template declares fits slot more than once.
PLAY0258	Error	A layout or a dialog template declares fits slot - neither fills a slot of a parent structure.
PLAY0259	Error	A top level layout line is not layout <Name>.
PLAY0260	Error	A document declares more than one layout by the same name.
PLAY0261	Error	A ui profile’s layout line is not layout <Name>.
PLAY0262	Error	A ui profile declares layout more than once.
PLAY0263	Warning	A ui profile selects a layout nothing in the document declares.

File references

Code	Severity	Reported when
PLAY0264	Warning	A file directive names an absolute path, and a file reference is relative to the repository root.

A path that does not resolve is not a diagnostic, at any severity. A document is read in a designer, in a build and on a machine where the tree is not present, so the compiler never holds a path against a file system - a stale path must not be what makes a valid document invalid. A consumer that can resolve paths decides for itself what an unresolvable one means.

Specification query results

Code	Severity	Reported when
PLAY0265	Error	A then query line does not name a query.
PLAY0266	Error	A line in a then query body is neither arguments nor result.
PLAY0267	Error	A then query assertion declares arguments more than once.

Semantic binding

Code	Severity	Reported when
PLAY0268	Error	Source syntax carries behavior the supported ESM profile cannot represent, including query filters with from, single-result filters, invalid same-name/scalar/type filter shapes, explicit query scopes and performers, compliance on identity or enum concepts, events combining personal or explicitly subject-scoped secret values with an explicit subject mark, generated properties whose concepts declare validation rules, and unsupported scalar $context produces paths (tenant is not event namespace; claims and roles are not portable scalar values), an unsupported validation rule, concept require, command require or production conditions over read-model paths (#129), date/today conditions, non-deterministic $env conditions, $context tag values, and a bare named rule with no implementation body (see Commands). Bodied named rules, command/concept code validation, and inline/file policy predicates bind as opaque ESM v3 attachments rather than reporting this diagnostic.
PLAY0269	Information	Source syntax is explicitly deferred from the current backend semantic profile.
PLAY0270	Information	Source syntax, including a valid persona, compliance reasons and event subject marks, is realization or authoring/operational metadata rather than portable behavior. Event id pins are executable stored names from ESM v16.
PLAY0271	Information or error	Source syntax keeps its legacy meaning and cannot be strengthened into ESM v1 implicitly.
PLAY0272	Error	Source syntax requires an explicit reviewed semantic migration before binding.
PLAY0273	Error	Syntax and identity information cannot produce a coherent semantic compilation, including reserved stored source Default or stream All names (also through id pins), stored-name collisions, an event-source for assertion without one unambiguous required scalar command destination type or a produces mapping, then event expectation, projection mapping, or constraint naming a property absent from the current event revision, or an authorization policy, property rule or requirement referencing a generated value before generation.
PLAY0274	Error	A syntax location cannot be mapped to a supplied semantic source document.

Specification event-source assertions

Code	Severity	Reported when
PLAY0275	Error	A specification event-source assertion is a bare for and does not provide a value.
PLAY0276	Error	One specification command or event step declares its for <value> event-source assertion more than once.

Projection variants

Code	Severity	Reported when
PLAY0277	Error	A variant line is not variant <Name>.
PLAY0278	Error	A variant declares no enters on event, so nothing ever activates it.
PLAY0279	Error	An enters on line is not enters on <EventType> [key <expression>].
PLAY0280	Error	A variant is declared inside another variant, and variants do not nest.
PLAY0281	Error	Two variants of the same projection declare the same name.

Opt-in completeness

These structural warnings run only when selected, after error-free whole-application source compilation. See Completeness checks for selection and exemptions and editor diagnostic support for the TypeScript/C# boundary.

Code	Severity	Reported when
PLAY0530	Warning (opt-in: --check data-bindings)	Visible screen bindings share a name but disagree on cardinality, resolved query or by parameter. Identical rebinding and sibling sections are allowed.
PLAY0531	Warning (opt-in: --check data-bindings)	A screen binding’s resolved read model or cardinality differs from its query’s return. Optional and observable qualifiers are ignored; unresolved or ambiguous names are skipped.
PLAY0532	Warning (opt-in: --check input-surfaces)	An action has no module-level command-bound form or issuing screen in the command’s own slice. Post-action navigation does not supply input; a title-only screen does not issue a command. Commands with only generated properties (including no properties) require no typed input.
PLAY0533	Warning (opt-in: --check input-surfaces)	A StateChange command has no used screen action or attached behavior execute, and no reaction invokes it. A form alone is not an issuer; attached navigation or open dialog may reach an issuing screen. Automation and Translate commands are exempt.
PLAY0534	Warning (opt-in: --check field-origins)	A declared read model has no builder or performer, or a top-level field lacks an identity, mapping, compatible AutoMap source, child or nested target. Variants are checked independently, including entering-event AutoMap; the owning slice’s keyed-query property counts as identity. Opaque builders and unknown coverage are skipped.
PLAY0535	Warning (opt-in: --check query-keys)	A query parameter cannot be held by its view’s known identity or fields. Identity comes from the owning slice’s unambiguous keyed-query property or structurally resolved projection keys. Performer-served views, tenant-context parameters and unknown identity types are skipped.
PLAY0536	Warning (opt-in: --check event-consumers)	The newest generation of a local event has no declared projection, reducer, reaction, constraint or interaction consumer. Specifications and production do not count. Imported external contracts are exempt; legitimate terminal facts may still be reported.
PLAY0537	Warning (opt-in: --check navigation)	A screen is unreachable from contributions or attached shell-level behaviors, including through screen actions, row clicks, behaviors, discovered forms or opened dialog templates. Unattached named behaviors and unreachable cycles do not establish entry points. With no entry points, one application finding reports that no screen is reachable.

Model consistency

These errors are reported by ordinary compilation, including compilation of a folder as one application; semantic binding is not required. References resolve from the innermost scope outward. Unknown or ambiguous declarations and imported shapes are not guessed.

Code	Severity	Reported when
PLAY0282	Error	A declarative validate rule targets a field absent from the command’s declared shape, including named rules with implementation blocks. A dotted path is followed through declared composite types; continuing past a primitive, concept or enum field is reported, while a path through an undeclared or imported type is left undecided.
PLAY0283	Error	The type supplied by reads <View> by <field> is incompatible with every declared query by parameter of that view. Filter parameters do not substitute for a key. Parameter names may differ; distinct concepts remain distinct types.
PLAY0284	Error	A children or nested block never populates a declared element field through its identity, explicit mappings, inherited every mappings, nested blocks, joins, or compatible AutoMap. Coverage is across the block’s events, not a requirement that every update event fill every field.
PLAY0285	Error	A specification’s expected event contradicts every possible declared producer of its when command, using decidable literals, property copies and equality conditions.
PLAY0286	Error	A specification value is not a member of the enum declared by that specific command, event, read-model field or query parameter. Bare members, qualified members and quoted member names are accepted.
PLAY0287	Error	A command or reaction producer, a capture append mapping, or a specification’s given/then event step, assigns a field absent from the referenced event’s declaration. Dotted paths follow the same rule as PLAY0282: title.missing is reported when title is a primitive, concept or enum, detail.missing when Detail is a declared type without that field. A collection or optional composite field is addressed element-wise.
PLAY0290	Warning	An import names an event, command, read model, concept or type the application declares itself. The declaration is what every reference resolves to and what these checks see, so the import has no effect - remove it.
PLAY0291	Error	A mapping value starts with { or [ but is not a valid single-line JSON object or list (keys must be quoted).
PLAY0292	Error	An object key does not name a property of the target’s declared composite type. Unknown or imported types remain undecided.
PLAY0293	Error	A statically known value has the wrong shape for its target: a collection expects a list, a declared composite expects an object, and a scalar cannot accept a list or object.
PLAY0294	Error	An inline JSON object repeats a key (including inside a nested object or list); each property may be stated once.

An import never changes what these checks see: a name the application declares resolves to that declaration whether or not it is also imported, and an imported name nothing here declares keeps an unknown shape.

These checks do not execute handlers, custom predicates or opaque expressions. An undeclared query signature does not establish a read-key mismatch. An unknown event shape under AutoMap, or an open all subscription with AutoMap, leaves projection coverage undecidable. Outcome checks compare explicit producer mappings only; they do not invent mappings for omitted fields.

Concept compliance markers, qualifiers and secret scopes are admitted by ESM v13. PLAY0268 refuses compliance on enum or event-source/stream identity concepts and refuses an event containing personal or explicitly subject-scoped secret values together with an explicit subject mark until lineage is admitted. The latter check is source/binder-only: subject marks have no ESM bytes. PLAY0515 still rejects protected identities during source validation. The strict reader and programmatic validator refuse compliance below v13, unknown special categories or scopes, secret scope next to personal, and compliance on enum or identity concepts. Reasons remain report-only (PLAY0270).

Caller-supplied equality filters on collection queries are admitted by ESM v14. PLAY0268 names the query, filter and reason for a refused filter: it has a from source, returns a single result, lacks a same-named scalar primitive/concept/enum property, differs in nominal type (ignoring optionality), repeats a name or duplicates by. Explicit scope, performer and context-sourced by each have their own refusal. The strict reader and evaluator reject unknown/repeated filter values, missing required filters, null and type mismatches. PLAY0468 applies to unknown/repeated/missing required specification arguments in both query spellings. See Queries.

For executable-model dispositions, see PLAY0268–PLAY0271 above, projection semantic-model admission, what the executable model admits for commands, and constraints.

AST authoring

Code	Severity	Reported when
PLAY0288	Warning	An accepted AST authoring operation canonically prints a touched document. The message states how many comments could not be retained and on which lines; attached comments follow their syntax owners, whitespace is normalized, and untouched documents retain their exact bytes.
PLAY0289	Error	An empty authoring workspace has no source documents to compile to an executable model. You can still propose its first typed document.

Source-authoring acceptance and executable readiness are separate verdicts. An authoring proposal validates the complete .play application and identity continuity without claiming that every language construct is supported by the executable backend profile. Executable-only workspace transactions remain strict.

Event context paths

Every $eventContext.<path> - in a projection expression or in a dynamic dictionary key such as countByType.$eventContext.eventType.id - is checked against the event context catalog. Chronicle resolves the path by reflection when it builds the projection and fails on one it cannot resolve, so this is the only place the mistake can be caught early. An unlisted member is a warning because a runtime may resolve more than the catalog lists; a path that can never resolve is an error.

Code	Severity	Reported when
PLAY0295	Warning	An $eventContext.<path> opens with a member the event context does not have, such as $eventContext.causationId. A member resolves written camelCase or with only its first letter uppercased.
PLAY0296	Warning	An $eventContext.<path> continues into something the member before it does not have, such as $eventContext.eventType.name. The derived function Week is case-sensitive: occurred.Week resolves and occurred.week does not.
PLAY0297	Error	An $eventContext.<path> continues below causation or tags. They are collections with no addressing grammar, so a path below them never resolves.
PLAY0298	Error	An $eventContext reference names no member, as in $eventContext. or a dynamic key ending in .$eventContext, or has an empty segment.
PLAY0299	Warning	A dynamic dictionary key names a $ source other than $eventContext, such as byUser.$causedBy.subject. Only $eventContext.<path> is resolved; any other source becomes the literal key. Write byUser.$eventContext.causedBy.subject.

Specification semantics

Code	Severity	Reported when
PLAY0350	Error	A command or event specification value is null; in Chronicle an optional fact is a separate event. Optional read-model values may be null.
PLAY0351	Error	A given readmodel or then readmodel block does not state every declared key part, or its inferred identifier when no key is declared. A scalar then query … result block may derive its identifier from the argument.
PLAY0352	Error	A specification without an action asserts an event or error, or has no read-state/query outcome. One actionless query with one error and no other outcome is admitted as a Validation rejection from ESM v18; an error without a query remains invalid.
PLAY0353	Error	A specification value is null for a required property, or a nested command/event property is null; only optional read-model properties admit null.
PLAY0354	Error	A structured specification object omits a required property of its declared composite type.
PLAY0355	Error	The composite type declared for a structured specification value cannot be resolved.
PLAY0356	Error	A typed structured specification object repeats a member; inline JSON duplicates are caught earlier by PLAY0294.
PLAY0357	Error	An ESM message beginning with $strings. has no valid dotted key. Keys follow .strings assignments: an ASCII letter or underscore first, then word characters; subsequent segments contain one or more word characters.
PLAY0358	Error	A specification declares more than one when action (command or appended event).
PLAY0359	Error	then events in any order is malformed or repeated.

Interaction

The interaction model - behaviors, the on clauses that start them, the actions they run and the continuations those actions branch into. The fifty codes from PLAY0300 upwards are reserved for this band as a whole, so a later addition lands beside its siblings rather than wherever there happened to be room.

A behavior is deferred from the backend ESM v1 profile in the same way every other UI construct is - see PLAY0269. Deferred does not mean droppable: the syntax tree, the printer and the semantic model carry every interaction construct in full, and a target that cannot realize one reports it rather than dropping it.

Code	Severity	Reported when
PLAY0300	Error	A behavior declaration is not of the form behavior <Name>.
PLAY0301	Error	A behavior name is declared more than once.
PLAY0302	Error	A line in a behavior body is neither description, parameter, order nor an on binding.
PLAY0303	Error	A behavior parameter declaration is not of the form parameter <name> [<Type>].
PLAY0304	Error	A behavior declares the same parameter name more than once.
PLAY0305	Error	A behavior order is not an integer.
PLAY0306	Warning	A behavior declares no bindings, so nothing it is attached to can run anything.
PLAY0307	Error	An on clause names neither a built-in interaction kind, an event, an interval, nor a declared application trigger.
PLAY0308	Error	An interaction binding declares no actions.
PLAY0309	Error	An interaction binding declares where more than once.
PLAY0310	Error	A line where an action was expected does not name one of the action kinds.
PLAY0311	Error	An execute action is not of the form execute <Command>.
PLAY0312	Error	A navigate action is neither navigate to <Screen> nor navigate back.
PLAY0313	Error	An open dialog action does not name a dialog template, or a close action is not close dialog.
PLAY0314	Error	A refresh action does not name a query.
PLAY0315	Error	A set action is not of the form set <target> to <value>.
PLAY0316	Error	A notify action is not of the form notify <info|warning|error> "<text>".
PLAY0317	Error	A confirm action carries no message.
PLAY0318	Error	A raise action does not name an application trigger.
PLAY0319	Error	An action argument is not of the form with <name> from <binding>.
PLAY0320	Error	A continuation is attached to an action that cannot fail, so it could never run. navigate, notify, set and close dialog have no outcome to branch on.
PLAY0321	Error	An on result continuation is attached to something other than open dialog.
PLAY0322	Error	A uses clause is not of the form uses <Behavior>.
PLAY0323	Error	An argument at a uses site is not of the form <parameter> <value>.
PLAY0324	Error	Interaction nesting went deeper than the compiler admits. Extract the inner actions into a named behavior.
PLAY0325	Warning	An interval trigger is below the floor a client can usefully honour.
PLAY0326	Error	An application trigger is declared with a name reserved as a built-in interaction kind. on <Name> would mean the interaction and never the trigger, so the declaration would be unreachable.
PLAY0330	Warning	An action names a command the document does not declare.
PLAY0331	Warning	A navigate to action names a screen the document does not declare.
PLAY0332	Warning	A refresh action names a query the document does not declare.
PLAY0333	Warning	An open dialog action names a dialog template the document does not declare.
PLAY0334	Warning	A raise action or an on clause names an application trigger the document does not declare.
PLAY0335	Warning	An on event clause names an event the document does not declare.
PLAY0336	Warning	A uses clause names a behavior the document does not declare.
PLAY0337	Error	A uses site supplies an argument the behavior declares no parameter for.
PLAY0338	Error	A uses site leaves a behavior parameter without an argument.
PLAY0339	Warning	Actions follow an unconditional navigation, so they could never run.
PLAY0340	Warning	Another file of a folder repeats an attachment of the same module or feature - a uses of the same behavior with the same arguments, or an inline on block identical to one already attached. Only the first, in file-path order, is kept; the repeat is ignored and the warning names the file that attached it first. Folders written by earlier versions restate a module’s or feature’s attachments in every descendant file, and report this once per copy.
PLAY0341	Error	A guarded action child is not when <condition> execute <Command>, otherwise hidden, otherwise execute <Command> or navigate to …; navigation is repeated, or otherwise hidden has command arguments.
PLAY0342	Error	A label-headed guarded action declares no when alternatives.
PLAY0343	Error	A guarded action repeats otherwise, or declares a when alternative after it.
PLAY0344	Error	A guarded action condition does not compare an item.<field> path with a literal. Ordering operators require a number; contains and starts with require a string.
PLAY0345	Warning	An item path in a guarded action condition or input binding names no subject field, continues past a scalar, or crosses a collection-valued field.
PLAY0346	Warning	A guarded action has no nearest data subject, or multiple data directives tie in its nearest container. Field checks are skipped until the subject resolves.
PLAY0347	Warning	Earlier alternatives provably shadow an alternative. Guards use first-match order; proof uses DNF comparison-set inclusion with a 64-disjunct expansion cap. Overlap alone is not reported.
PLAY0348	Warning	A guarded alternative or otherwise execute supplies a with argument the chosen command does not declare, or binds a subject field whose collection cardinality differs from the command input.

Guarded-action checks PLAY0341–PLAY0348 are shared by the TypeScript compiler, Monaco and VS Code. Subject and command shapes that are imported but undeclared, or ambiguous, remain unknown rather than guessed. See Editor diagnostic support for the remaining C#-only checks.

An inline on block is an anonymous behavior, so it has no name to report against. Diagnostics inside one cite the position and the trigger instead.

Match validation binding

Code	Severity	Reported when
PLAY0366	Error	A bare named matches pattern is not defined; only email is defined. Use a quoted ECMAScript pattern for custom matching.
PLAY0367	Error	A quoted matches operand is not a valid ECMAScript regular expression.
PLAY0368	Error	A validation rule names a severity other than information, warning or error.
PLAY0369	Error	A require body has an invalid or repeated severity directive.

Projection binding

Code	Severity	Reported when
PLAY0380	Warning	A projection construct binds, but Chronicle’s projection lowering drops part of it: all inside a children or nested block loses its subscription to every event type and behaves as every, and an automap or no automap on a joined event is replaced by the auto-map of the level the join sits in.
PLAY0381	Warning	A projection-level key is parsed but does not route events in Chronicle or the executable semantic model. Declare keys on each from (or its events).
PLAY0382	Error	A variant declares no enters on event.
PLAY0383	Error	A projection-level shared handler maps a property absent from a variant’s known read-model shape. Unknown shapes remain undecided.
PLAY0384	Error	Two variants in one projection have the same name.
PLAY0385	Error	An entering event is claimed more than once in one projection.
PLAY0386	Error	A given caller line is not authenticated, role "<name>", or claim "<type>" = "<value>".
PLAY0387	Error	A specification declares more than one given caller block or then denied outcome.
PLAY0388	Error	then denied contains extra text or is mixed with another outcome.
PLAY0389	Error	A specification exercises an authorized command or query without a given caller fixture or given caller as <Persona>.

Constraints in the semantic model

These diagnostics cover constraint binding and the parser warning for file-backed constraints.

Code	Severity	Reported when
PLAY0390	Error	A unique constraint names an event the application does not declare.
PLAY0391	Error	A unique <property> on <Event> constraint names a property the event does not declare.
PLAY0392	Error	Two constraints in the application share a name. The name is a constraint’s identity in the event store - it keys the constraint’s index and its violations - so it is unique across the whole application, not just its slice.
PLAY0393	Error	ignore casing is declared on a unique event constraint; it applies only to unique property values.
PLAY0394	Warning	Another file declares an identical authorize gate on the same module or feature. The first is kept and the repeated gate is ignored; distinct gates accumulate with AND.
PLAY0396	Warning	A file <Path> constraint names a Chronicle IConstraint class, which can only declare uniqueness. Use unique ... for portable uniqueness; put other rules in command validation or a require condition.

Inline code migration

Use an opening fence with an info string, such as ```csharp (without the spaces), for every inline implementation. Use ```text for multiline descriptions. The old language-line form, validate csharp, and bare description fences still parse during the deprecation window; printing a document converts them to the new form.

Code	Severity	Reported when
PLAY0397	Warning	An inline code block uses a separate language line, validate csharp, or a multiline description uses a bare fence. The message names the tagged-fence replacement.

A compiler-authored typed repair is offered only when PLAY0397 identifies a validate csharp header. It uses an identity replacement and canonical printing to produce a tagged ```csharp fence. The entire file is reprinted; other legacy forms and whitespace may change, but a repair that would drop any comment is refused. Preview it through the revision-checked AST authoring contract (or MCP read-workspace repairs / propose-repair); review the bytes before applying. Other legacy forms are not individually offered as repairs.

Repeated command or reaction-trigger reads

Code	Severity	Reported when
PLAY0410	Error	A command or reaction trigger reads the same view more than once without an alias on every instance.
PLAY0411	Error	Two reads in a command or reaction trigger use the same alias.
PLAY0412	Error	A reads alias collides with a command property or reaction trigger value.

Implementation attachment loading (host-supplied)

These warnings are returned by AttachmentFiles.Load for implementation files that remain UnresolvedFile. Syntax compilation alone does not read files.

Code	Severity	Reported when
PLAY0430	Warning	An attachment path is absolute, drive-qualified, escapes the model root, or is not portable.
PLAY0431	Warning	An attachment or a directory on its path is a symbolic link or reparse point.
PLAY0432	Warning	An attachment or a directory on its path is missing.
PLAY0433	Warning	An attachment exceeds 2 MiB or the attachment set exceeds 8 MiB.
PLAY0434	Warning	An attachment cannot safely be read as UTF-8 text.

Executable semantic model

Code	Severity	Reported when
PLAY0445	Warning	A v1–v3 flat executable-model projection transition carries deprecated ZeroOrOne or Many affected-instance cardinality. Chronicle routes one key per transition; use a join for structural many. Returned by ExecutableSemanticModel.DeprecationDiagnostics for constructed or deserialized ESM, with a model-level location because ESM does not retain source positions. The source binder produces only One; query cardinality is unaffected.
PLAY0449	Error	A given fact needs a historical event shape (message names the event and revision), which Screenplay does not consume yet; or an event’s source revision disagrees with its persisted catalog revision and requires explicit forward advancement. There is no fallback from current to historical properties.

File imports

See Imports.

Code	Severity	Reported when
PLAY0454	Error	An import inside a module or feature does not name files as import "<path or glob>".
PLAY0455	Warning	A file import pattern with wildcards matches no .play file.
PLAY0456	Error	A file import names one file, without wildcards, and that file does not exist.
PLAY0457	Error	Two imports place the same file in a module or feature where neither lies inside the other. A file belongs in one place.
PLAY0458	Error	Imports keep placing a file deeper than 32 levels - they form a cycle.
PLAY0459	Error	A file imported into a module or feature declares a module other than the one it is placed in. Restating the module it is placed in is allowed.
PLAY0460	Error	The top level of a file imported into a module or feature holds something that scope cannot hold, such as a screen template in a file placed in a feature.

Refusal branches, redelivery and no-event assertions

Refusal branches and $refusal values bind and execute from ESM v19. Redelivery and then no events bind and execute from ESM v17; earlier strict readers reject their respective canonical members.

Code	Severity	Meaning
PLAY0538	Error	An on refused header is malformed, uses an unsupported selector, or appears outside an invokes block. Use on refused [by validation | by constraint [<Name>] | by authorization].
PLAY0539	Error	A refusal branch is empty, repeats or adds children to acknowledge, combines acknowledgement with productions, or contains another kind of effect. Use acknowledge alone or one or more produces <Event> blocks.
PLAY0540	Warning	A refusal branch is shadowed by an earlier selector, or its declared constraint targets none of the invoked command’s events. Bare refusal covers validation and constraints, not authorization.
PLAY0541	Error	A $refusal value is outside a branch’s event mapping, has an unknown member, uses constraint outside a constraint selector, or targets an incompatible property type. The values reason, constraint and message are String values.
PLAY0542	Error	A named constraint in a refusal selector does not resolve to a declared constraint.
PLAY0557	Warning	An on refused by authorization branch invokes a command gated by its own, feature or module authorization without a declared invoking identity. With no caller the reference runner always refuses the command. Arc runs commands as the system only for a reactor carrying [ExecuteCommandsAsSystem]. Declare runs as system role "<Role>" to state the intended identity; it suppresses this warning and selects released ESM v10. Refusal branches select ESM v19.
PLAY0543	Error	when redelivered <Event> to <Reaction> is malformed, or its values, optional for and route locator do not identify exactly one definitely matching given event occurrence with no undecidable candidates. Use for, values, stream or no stream to narrow the locator.
PLAY0544	Error	The redelivery reaction is unknown or ambiguous, or has no event trigger on the stated event.
PLAY0545	Error	then no events is malformed, repeated, has child mappings, or accompanies event, event-order, error or denial expectations. Use one leaf assertion after an action, including when append; read-model, query and response assertions may accompany it.

Reaction command identity

runs as is admitted by released ESM v10; PLAY0268 no longer refuses reaction command identity. Omitting it preserves existing executable bytes. System claim conditions evaluate to unknown and a final unknown denies.

Code	Severity	Meaning
PLAY0647	Error	runs as is malformed, repeated or misplaced, or contains an empty or duplicate role. Use one reaction-level runs as system [role "<Role>" and role "<Role>"] line. Roles are quoted literals; zero roles is allowed.
PLAY0648	Warning	A reaction invokes a command with its own or inherited authorization gate without declaring runs as. Both compilers report at most one finding per invocation; an authorization refusal branch receives PLAY0557 instead.
PLAY0649	Warning	The reaction declares identity but has neither invocations nor an inline or file implementation body. Both compilers check this.
PLAY0650	Warning	C# binder only: a declared role is referenced by no invoked command’s effective gate. Opaque gates and inline or file reaction bodies suppress this least-privilege finding.
PLAY0651	Warning	C# binder only: the declared system identity definitely cannot satisfy an invoked command’s effective gate. Claim conditions and other unknown results are not treated as definite denial.
PLAY0652	Warning / Information	Opt-in privilege completeness: each producer of an elevated reaction’s trigger event must require every declared system role. Ungated commands, captures and reaction productions produce Warning; opaque gates produce Information because they cannot be compared. Clock and application triggers have no producer and are silent.

See Refusal branches, Redelivery specifications and Specification syntax.

Specification actions

See Specifications.

Code	Severity	Reported when
PLAY0461	Error	A given clock or when clock does not state one ISO 8601 instant with an offset or Z, or given clock is repeated.
PLAY0462	Error	A when trigger line is not when trigger <Trigger>.
PLAY0463	Error	A given capture or when capture line is not <given|when> capture <Capture>.
PLAY0464	Error	A when query line is not when query <Query>, a then result line is not then result [exactly], or then no result is malformed or repeated.
PLAY0465	Error	A query result is asserted without when query, a performed query asserts no outcome, results conflict with no result, or a query error is combined with an action, multiple calls/errors, a result, then no result, denial or another outcome. Both compilers share the query-error shape checks; executable v18 admission and Validation comparison remain C# checks.
PLAY0466	Warning	A when trigger names a trigger nothing declares or registers, or a value its declaration does not carry.
PLAY0467	Warning	A given capture or when capture names a capture the application does not declare.
PLAY0468	Error	A when query or then query … arguments argument is unknown or repeated, or a required by or filter argument is missing.

Inline event declarations and metadata

These codes cover inline command events and event metadata.

Code	Severity	Reported when
PLAY0469	Warning (inline), information (plain)	A production copies the command identifier into payload while targeting that same identifier. The inline-only repair removes the property and mapping, explicitly changes the event contract, retires its property address, and is excluded from fix-all. Consumers, opaque implementation impact or comment loss refuse the repair. Plain/standalone contracts receive guidance only: review persistence and generation evolution before changing their shape.
PLAY0470	Error	A command targets another event source but one or more productions omit for, or both an inline and a plain production omit for and therefore have different defaults. The diagnostic names the production. State every destination explicitly; cross-source execution is still unsupported.
PLAY0471	Information	An event’s id equals its current name. The typed removal repair covers inline and standalone declarations, preserves the executable model and catalog, and refuses comment loss. Monaco and VS Code also offer an editor quick fix to remove the complete line unless it has a trailing comment.
PLAY0472	Error	Event id is missing its nonempty quoted value or is repeated.
PLAY0686	Warning (retired)	No longer reported: ESM v16 carries event id pins as stored type names under decision 0075. Retained for compatibility with earlier compiler warnings. See event rename pins.
PLAY0473	Error	An inline event name collides with a standalone declaration, import, or another inline declaration.
PLAY0474	Error	produces event occurs outside a command, such as in a reaction.
PLAY0475	Error	An inline event declares generation in its header or body. Extract it before evolving generations.
PLAY0476	Error	A production supplies unescaped system-assigned namespace, sequence, correlation, causation, causedBy, or occurred, or an inline event supplies origin.
PLAY0477	Error	Event documentation is not one nonempty fenced Markdown block, or is repeated.
PLAY0558	Error	Module, feature, slice, command, read-model or reaction documentation is not one nonempty fenced Markdown block, or is repeated.
PLAY0559	Warning	Files give different documentation for one module or feature. The first documentation is kept.
PLAY0572	Error	A given caller as <Persona> reference is malformed, has body lines, or names an unknown top-level persona. Unknown references list declared personas.
PLAY0573	Error	A persona caller cannot be synthesized or verified against its policies. Binding names the persona, policy and refusal (negation, nonLiteralClaim, roleClaim, opaqueImplementation, unresolvedPolicy, noPolicies); use an explicit given caller.
PLAY0574	Warning	Opt-in personas check: none of a persona’s policies gates a command, query or inherited screen scope.
PLAY0575	Warning	Opt-in personas check: an effective command or query gate definitely denies every declared persona’s synthesized caller; unsynthesizable or undecidable callers are unknown.
PLAY0576	Information	Opt-in personas check: required atoms do not pin an or with multiple buildable alternatives. Names an unchosen alternative and suggests adding a policy that pins it.

Malformed typed mappings and duplicate destinations retain PLAY0044 and PLAY0193. Descriptions retain their existing diagnostics. Event descriptions and documentation retain their information diagnostic (PLAY0270). Event rename pins that differ from the event name select ESM v16 and carry storedName; equal-name pins keep the earlier version and bytes, and PLAY0686 is retired. Invalid pins, generation disagreements and stored-name collisions use PLAY0472.

Production destination advice and repairs

Code	Severity	Reported when
PLAY0478	Information	A plain produces <Event> omits for and its command has one required scalar identifier. Conditional productions and optional or collection identifiers are not reported.

PLAY0478 does not change routing or executable-model bytes. Its typed repair replaces the production with one that explicitly states for <identifier>. Accept it only when that event should address the command’s identifier: a plain omission can intentionally use an allocated identity, or inherit another production’s explicit destination. The repair is not offered for an optional or collection identifier. It is also refused when the original or candidate has no executable model, when the repair would change the language or semantic version, or when any other production’s effective destination would change (including through a command default). Discovery verifies these conditions and comment preservation once per subject on an immutable workspace snapshot; a new snapshot cannot reuse those verification results.

The verified PLAY0478 repair is available through the MCP repair workflow. Monaco and VS Code do not offer a quick fix for PLAY0478 or PLAY0470.

For PLAY0166 on a command production, a typed repair can add an event declaration to the producing slice. Properties follow mapping order; command property paths retain their types and concepts (including compliance markings), and $context.occurred becomes DateTime. No generation, tags, subject or origin is inferred. Unknown sources, literals, computations, reads, conflicting producer shapes, imported or already-declared events, and cross-file producers have no repair. Any workspace document with parser errors also blocks inference, because its partial syntax may hide a contract or another producer. Reaction and capture producers are not inferred.

Both repairs require canonical formatting consent and refuse any dropped comment. Discovery verifies authoring acceptance for PLAY0166 too: an inferred event whose fields conflict with a specification is not offered. Discovery reuses cached acceptance and conflicts on the same immutable workspace snapshot; diagnostics are never cached. Every proposal runs one fresh transaction, even after discovery. A matched repair that fails returns that transaction’s typed conflicts and full diagnostics; UnknownRepair means no recipe matches the code and original subject, not a verification failure. Discovery and preview never write source. Review the write plan and explicitly accept it through the workspace authoring contract or MCP repair workflow. Stale workspace or catalog revisions are rejected. Source authoring and executable readiness remain separate; for example, compliance attributes and nested mapping paths can require capabilities the executable model does not yet admit.

Optional values and spelling repairs

Code	Severity	Reported when
PLAY0479	Information	A type uses the legacy optional suffix. Write optional after the type. This does not fail --warnaserror.
PLAY0480	Error	optional follows identifier. Write the modifiers in the order Type optional identifier; command identifiers must still be required and scalar.
PLAY0481	Error	A read uses optional. Optional reads are not yet supported; their absence behavior is reserved for #308.

query Q => observable? is the sole exception: its ? is the only spelling that preserves a one-shot query returning an optional scalar type named observable. It produces no PLAY0479 and is excluded from occurrence repairs and document migrations. See Queries.

PLAY0479 points at the complete type reference. VS Code marks it deprecated. Its workspace repair replaces only the spelling at that occurrence; a document repair combines all such replacements in one verified transaction. Both reparse the result, require unchanged syntax structure, and check that the selected information diagnostics disappear. Use PreserveTrivia to keep comments, alignment, line endings and encoding. Canonical reprinting is a separate explicit choice. Discovery and preview never write files; acceptance still requires current workspace and catalog revisions. Monaco and VS Code also offer verified TypeScript quick fixes for one occurrence or the entire document, without requiring .NET.

Generated values and command responses

Generated properties, command responses, generated fixtures and return expectations are admitted as ESM v7. A pre-generation reference from authorization (including inherited/composed policies or a generated identifier’s implicit subject), a property rule or a requirement reports PLAY0273: reference an input property or remove generated. Rules on a generated concept select ESM V20: Proven rules are silent, Refuted rules report PLAY0688 with a witness and Unproven rules report PLAY0689 with a reason. Earlier ESM readers refuse these rules rather than drop them; fixtures are checked after shape validation, with failures rejected as Contract and opaque predicates remaining Unsupported. Missing generation fixtures bind, but reached generation returns Unsupported(IdentityAllocation) and cannot pass a specification. Other unadmitted constructs still block executable binding. See commands and fixtures.

For response and generated-fixture compatibility checks only, Date values must be quoted yyyy-MM-dd calendar dates. DateTime values must be quoted yyyy-MM-ddTHH:mm:ss, optionally followed by a decimal fraction of 1–7 digits, and always end in uppercase Z or an explicit +HH:mm / -HH:mm offset. Years range from 0001 to 9999; calendar days must exist, hours range from 00 to 23, and minutes and seconds from 00 to 59. Offsets range from -14:00 to +14:00; at 14 hours the minutes must be 00. These checks do not change general literal parsing. Imported or unresolved value shapes remain unknown rather than being inferred from their names.

Code	Severity	Reported when
PLAY0482	Error	A generated property is declared outside a command.
PLAY0483	Error	A generated property is not a required, noncollection generatable concept (implicit Uuid uuid or an explicit generation declaration).
PLAY0484	Error	Property modifiers repeat or are out of order. Write Type optional generated identifier.
PLAY0485	Error	A generated property is supplied as request or form input.
PLAY0486	Error	A command response is malformed, empty, repeated or conditional.
PLAY0487	Error	A response source does not reference one direct command property.
PLAY0488	Error	A response block repeats a field name.
PLAY0489	Error	A response uses a collection or whole read model, or an explicit field type differs from its source’s type, collection shape or optionality.
PLAY0490	Error	A generated fixture repeats a target, names an unknown, nongenerated or identifier property, or supplies an incompatible or nonconcrete value.
PLAY0491	Error	A return expectation is malformed, repeated, incompatible with the response contract, lacks a command action, or accompanies an error or denial.

Handler implementation intent

Code	Severity	Reported when
PLAY0492	Error	An implementation wrapper has an operand, duplicate wrapper, unknown child or nested file child.
PLAY0493	Error	A hint is not one nonblank quoted string, or has children.
PLAY0494	Error	A handler mixes direct/wrapped sources, or a wrapper selects more than one file/inline payload.

These wrapper diagnostics also apply to operation phases. Pending or attached intent is not executable admission.

Operations and external systems

Code	Severity	Reported when
PLAY0495	Error	An external system declaration is malformed or repeated.
PLAY0496	Error	An operation declaration or phase is malformed, or supplies event-only metadata.
PLAY0497	Error	A production reference is ambiguous, or a qualified production does not resolve to an explicit operation.
PLAY0498	Error	An operation name collides with an event or another operation in its owning slice.
PLAY0499	Error	An operation is produced outside a command.
PLAY0500	Error	An operation must reference exactly one uniquely declared external system.
PLAY0501	Error	An operation input mapping is missing, repeated, unknown or incompatible with its declared type.
PLAY0502	Error	An operation specification step is malformed, unresolved, duplicated, incompatible with its command action or asserts undeclared compensation.
PLAY0508	Error	A numeric preamble has an unknown or malformed spelling, or a numbers exact document nests another numbers directive inside a declaration; only a top-level numbers exact is recognized.
PLAY0509	Error	A physical document repeats its numeric preamble.
PLAY0510	Error	A numeric preamble follows domain, imports or declarations.
PLAY0511	Error	A complete number cannot be represented exactly in the bounded Decimal domain.
PLAY0512	Error	Declaration-bearing physical documents or marked import barrels disagree on numeric mode.
PLAY0513	Error	Source options or inserted numeric values disagree with their owning mode.

The numeric rows are syntax diagnostics. A valid numbers exact document still cannot bind: PLAY0268 reports that exact numeric mode is not admitted by any supported executable model (ESM) version yet, and unmarked documents keep their existing numeric behavior.

These are syntax diagnostics. A valid system, operation or operation specification still cannot bind: PLAY0268 reports that these constructs are not admitted by any supported executable model (ESM) version yet. Operations do not trigger event destination or payload-identity diagnostics. A valid pending or attached handler remains unsupported independently. Diagnostic repairs for PLAY0471 and PLAY0479 are unchanged.

Timeline order

Code	Severity	Reported when
PLAY0516	Information	A projection, reducer rule or named reaction trigger uses an event from a later slice, or a command/reaction reads a read model built by a later slice (builder preferred over declaring slice). Reported once per consumer slice and event or read model at its first reference. Reads whose builder’s projections or reducers for the read model being read consume any event produced inside the reader’s child at the reader/builder’s lowest common container are excluded, including from cycle grouping. Projections with a matching variant count, including their shared blocks and variant transitions; unrelated projections and reducers in the same slice do not. Produced events include declarations and command/reaction produces targets, including imported events. A producer in the consumer’s own sub-feature cannot be fixed by reordering. This does not fail --warnaserror.
PLAY0517	Information	A sibling group depends on each other’s events or non-feedback read models, so reordering cannot make every dependency flow left to right. Reported once per mutually dependent group, at its earliest backward reference, instead of individual PLAY0516 findings within that group. This does not fail --warnaserror.

See Timeline diagnostics for the ordering root, grouping rules, checked references and C#/MCP repair conditions. PLAY0516 offers verified typed moves or explicit pins before a retained glob where safe; PLAY0517 and own-sub-feature findings have no repair. These findings and repairs do not change executable behavior.

Declared dependencies

Code	Severity	Reported when
PLAY0552	Warning	An opted-in container has uncovered counted references into a producer module. One finding per container and producer module, at the container header, with source evidence. If the producers’ shared container is an invalid ancestor target, the finding lists their outermost covering-eligible features instead.
PLAY0553	Information	A valid declaration has no counted explicit reference, including provisional ambiguous coverage. Reported at the declaration.
PLAY0556	Information	Two containers declare each other. Reported on each declaring line.
PLAY0554	Warning	A depends on target is self, an ancestor, a descendant, or does not resolve to a module or feature.
PLAY0555	Warning	The same target is declared again on a container, in one file or across files. Resolved aliases count as repeats; unresolved targets compare by text. The first is kept.

An ambiguous target uses PLAY0198, naming the equally near candidates. See Declared dependencies for the sibling and qualified-name rules. Malformed statements are parse errors (PLAY0022 in a module, PLAY0024 in a feature).

Event sources and command streams

Code	Condition
PLAY0503	Invalid or duplicate source/stream declaration, including non-scalar types or invalid composite part declarations
PLAY0504	Missing or ambiguous source-owned stream, invalid scalar/composite key mapping or literal formatting, or known incompatible command identifier, production destination or key type
PLAY0505	Both the route and qualified value-property interpretations are viable; neither is selected
PLAY0506	Known scalar or composite part type needs an unsupported portable formatter; bare Int is not supported
PLAY0507	Redundant rename-only stored-name pin
PLAY0547	Invalid, empty, duplicated, conflicting or misplaced specification route/part block
PLAY0548	Specification command occurrence declares routing metadata
PLAY0549	Unresolved specification route or missing, unknown, duplicated, mismatched-shape, nonliteral, incompatible or unformattable stream id/part
PLAY0550	Missing or incompatible routed source identity, or ambiguous producer fallback without a source identifier
PLAY0551	Expected route contradicts its sole producer, the command under test

Valid source/stream authoring selects ESM v8. Executable mappings use direct required, non-collection, non-generated command properties or literals; property paths and handler commands still fail with PLAY0268. Editors and MCP preserve original source evidence; unknown imported type shapes are not guessed. There is no new routing or source-pin quick fix. Existing PLAY0470/PLAY0478 repairs still refuse when executable before/after routing proof is unavailable.

Negated claim targets

Code	Severity	Reported when
PLAY0546	Warning	Semantic binding applies a policy with a claim under not, directly or through grouping, whose target is an optional path, a command’s subject without an identifier, or a non-string type. An undecidable target evaluates to unknown even under negation; a final unknown policy result denies. Reported at the authorization reference against that command’s properties or query argument. The TypeScript syntax compiler does not perform this semantic check.

See Policies for three-valued evaluation and the distinction between a missing caller claim and a missing comparison target.

Guarded interaction alternatives

Code	Severity	Reported when
PLAY0560	Error	Alternatives occur on a trigger other than click, double click or select. Submit and non-item triggers have no structured subject in this version.
PLAY0561	Error	A binding mixes alternatives with plain actions or an opaque where guard.
PLAY0562	Error	A when or otherwise branch has no actions.
PLAY0563	Error	An interaction uses the labeled-action one-line when … execute … spelling. C# offers a typed block-form repair.
PLAY0564	Warning / Information	Opaque where on click, double click or select is deprecated. A strict item condition warns and has a C# typed repair; other text is Information without a repair. Other triggers are unchanged.

Both compilers check these forms. Repairs require individual review (CanFixAll: false) and refuse trailing-comment relocation or comment loss. Conditions reuse PLAY0344–PLAY0348; fallback ordering uses PLAY0343 and missing alternatives uses PLAY0342. See Interactions. Interactions still report PLAY0269 at ESM binding; syntax support is not runtime admission.

Specification case tables

Code	Severity	Meaning
PLAY0577	Error	A parameter requires a name and property-line type, without a body or default.
PLAY0578	Error	A case requires an identifier and at most one inline assignment.
PLAY0579	Error	A parameter name is repeated within a table.
PLAY0580	Error	A case name is repeated within a table.
PLAY0581	Error	Tables require parameters and at least one case.
PLAY0582	Error	A case omits, repeats or invents a parameter assignment.
PLAY0583	Error	A case value is not concrete or cannot be normalized to its declared parameter type.
PLAY0584	Error	A case reference names no declared table parameter or occurs in an excluded position.
PLAY0585	Error	An optional parameter feeds a required target.
PLAY0586	Error	A derived specification name collides in its scope.
PLAY0587	Error	The parameter type is unknown or incompatible with its target type.
PLAY0588	Warning	A declared parameter is never referenced.
PLAY0589	Error	Singular effective expansion cannot represent a table; use ExpandAll.

See Named case tables.

Retired codes

A retired code stays out of use forever.

Code	Retired in	Replacement
PLAY0176	v4.25.0	Repeated reads without aliases are reported as PLAY0410.
PLAY0686	v4.152.0	Event rename pins that differ from the name are carried as storedName in ESM v16 (decision 0075); no warning is needed.